I am a high school science teacher in N Alabama. I am looking to raise BSF on a small scale in our classroom. Is there anything that I can use as a medim to 1 keep smell to a minimum? 2 keep the sludge from forming at the bottom. Id like to try to feed wet chicken feed and veggie waste from the lunchroom. I will consider going larger scale once the weather warms up and we can go outside. Any help would be appreciated.

Jengland welcome to our forum If you'd like you can introduce yourself here (link).

Check out this thread for ideas Small Scale Indoor Breeding topic (link).

I would also caution you to not overfeed your bin which results in smells from the feed rotting before it can be consumed.

Can I use Coco fiber as a substrate?

Coco fiber will work as a substrate. You may want to separate the area where the larvae feed from where they'll eventually pupate. The latter is where coco fiber can be used as a medium for the larvae to burrow into to get away form the light (they're photophobic).

I was referring more to a substrate for the grow bins. Maybe feeding in a corner. I was hoping to avoid the food sludge they normally reside in.

My bin is made from a storage tote. Is that about the size you're thinking of?

I have a couple of margarine tubs (2lb size) in the bin which I feed in. Tried a drainage system in these consisting of a false bottom made from landscape fabric but it quickly 'silted' off from the fine particals in the frass. Now I just manage the moisture by feeding wetter or drier material as required.

If you're wondering how the large scale folks to this I believe they're using feed stocks which are dry like spent brewers grains or similar. These are easy to manage and also allow the larve to be harvested by screening/sifting.